In a cluster topology, the keyspace is divided into hash slots. Different nodes will hold a subset of hash slots.

Multiple keys operations, transactions, or Lua scripts involving multiple keys are allowed only if all the keys involved are in hash slots belonging to the same node.

Redis Cluster implements all the single key commands available in the non-distributed version of Redis. Commands performing complex multi-key operations like Set type unions or intersections are implemented as well as long as the keys all belong to the same node.